Stoker furnace



Sept- 11, 1951 J. s. BENNETT 2,567,837

STOKER FURNACE Filed Nov. 2, 1946 v 5 Sheets-Sheet l Figi TTO/e/VE YSept. 11, 1951 J. s. BENNETT 2,567,837

sToKER FURNACE ATTORNEY Patented Sept. 11; V1951 UNITED STATES PATENT4Ol'fllGE STOKER FURN'ACE .Joseph S; Bennett, Merian, Pa., assignor toAmericany Engineering Company, Philadelphia, Pa., v

a corporationof Pennsylvania, Application November 2, 1946; Serial No.707;425 f In order to obtain maximum capacities and?"v efficienciesinsteam powervpl'ants, it is necessary that the entirel grate area of thefurnace be elfectively utilized toburnl the fuel Asupplied thereto. Oneof the problems encountered in stokers-'employed in' thelargerinstallations is in effectively feeding and distributing fuel so'thatthe entireavailable grateV surfacewill be utilized effectively.Inmany'ofv the modern power plants the boilers installed are ofconsiderable depth from front to rear of the furnace; VIny such furnacesit has been found that the vfuel feeding devices of the stokersheretofore employed were inadequate to feed and distribute the fuel"such a` manner that the-required capacities'and efficienciesthereof'could be obtained'. This has been found to be true regardless of'the type of stokers employed' feeding fuel over relatively longdistances ifi roduces "many problems both in connection with the AfuelAvfeeding and distributing mechanism'ernpl'oyed and dueto slag andclinker formations which greatlyimpair proper operation ofA theVfurnace. Y

One object of the present invention is to provide novel furnaceconstructions which eliminate the various problems heretoforeencountered and which; enable operation of the furnaceV at the maximumcapacities 'and e'ciencies.

Another object is to provide a novel furnace wherein feeding' of thefueliis eifected'at' the sidev thereof rather 'than at the front or rearofthe furnace asis usually the case.

A further object is .to provide anovel furnace furnaces of the characterdescribed water-cooled. screens between the Various stoker units, the

tubes of the .said water-cooled screens being, so arranged as tofacilitate the passage of combustion gases therebetween;

VA still furtherk object/isto provide in .furnaces of the characterdescribed one `or more Stokerr units of the. traveling grate spreadertype.

3 claims. V(cl. 122-235) 2 e Other andE further objects will becomeapparent asthe description. of; the. invention progresses.

Ofthe drawings:

Fig. l-fis. a' longitudinal sectional elevational View ofthefurnac'e,fshowing the arrangement of? theavariouselements thereof.

Fig.- 2 is a 'transverse Asectional'-elevational, view takensubstantially-along Vline 2'2. of Fig. 1.

Fig.- 3- is a-1planfview, partly' in section, takenYsubstantially-'along line 3--3 of Fig. 2'.

Figi Lllisea sectional view of the tubes of afpon-v tion of' one of 'thewatencooled screens ltaken substantially'alongjlinelle-4 of Fig.. 1.

Fig.` 5I is a transverse sectionalelevational View of a furnace 'of analternative construction.

` Fig. tiV is a plan view, partly in section-taken substantially along4line 6-6 of Fig;` 5.

' Fig. 'Zis a sectionalviewfof the'tubes of a portion-of one ofthewater-cooledscre'ens takensubstantially along line 'I-'l of Fig. 5.

Referring' tothe drawings, fand 'more particularly to Figs. 1 to 3'thereof, themuneral I designates `generallya furnace comprising frontand rearv walls 2 and 3f respectively and side walls 4- and 5'-,VExtendingf'between sidewalls 4 and 5 and forming'the"bottorn'wall ofthecombustion chamber 6# ofthe furnace are three units l, 8 and lStof VaStoker 'indicated lgenerally 'at I'll.

yMounted in any suitable'fmannerincombustion chamber 6is a boilerl l.Boiler Il may be of'anyfsuitableftype and, as illustrated, comprises.three steam drumslz, I-S-'and i4 and a mud drum l5. Banks of tubes I6,llandf I8, ofusual construction, extend #betweenand -are connected tosteam drums-v l2, l`3l-a^nd'"Utrespectvely and nmud" drum'j l5lVl'a'nksof"y tubes l5 and 12D' also connectf steam drums '-I'2 and I`4-tosteam drum-|`3. A lowerbaiile 21= andan upper baffle 2'la,extendingresp'ectively from#y the l'rear and front ends lof the combustioncham-ber transversely over the stoker'sectonsdire'ct the flow ofcombustion gasesy from? the -stok'ei 'sections'fto and over! a commonpatlrftraversing thedr-ums and'itube's'of the' boiler.` Battles;4 21e;Zibiandf 2lu of: 'usuali construction, compelnthe furnace gases tofollow the fdirection of the arrows inl'ig:l l'to` the" lower" "e'nd lofan economizer f'muntedf adjacent rearA Wall 3f and indicated generallybyI numeral 25. The furnace gases nowupwardlyin econornzer '25 andfintoa duct 26 connect'edtothe inlet side of' an inducV tion fanZlffrom'whichfthe gases arey conducted to the stack 28 of the furnaceyby an outletk duct. 29; .Fan-121. and` duct 26k are. mounted on anysuitable supporting structure 3l)` disposed a short distance {beneath--the root lfrof. the .furnace I.

lower end of side wall 5. Branch ducts 36, 31

and 38 connect communicating duct 35 with plenum chambers 39, 4|) and 4|provided respectively beneath stoker units 1, 8 and 9.

The lower portion 43 of bale 2| is spaced a short distance from mud drum|5. As a result any cinders or fly ash settling on mud drum |5 will-pass between the tubes of bank I6 and onto a deflector plate 44.Deflector plate 44 conducts the cinders and y ash toa hopper 45 providedadjacent the lower .end of economiZer 25. A valve 46 isprovided. atthelower end of hopper 45 through which the cindersand fly ash may pass toa second hopper 45a. disposed therebeneath. A second hopper 41 isconnected to the lower end of economizer 25 for receiving any cinders orfly ash settling in the latter as the furnace gases flow therethrough;`A valve 48 is provided at the lower end of hopper 41 through which thecinders and fly ash collecting in said hopper may pass to a secondhopper 41a. Hoppers 45a and 41a are connected to any suitable blower,indicated at 49, having a spout 498b connected to the discharge sidethereof. The cinders and fly ash deliveredl to spout 492L by blower 49are conducted thereby to any suitable place of disposal. A. sealingplate 44a extends between mud drum l5 yand the lower end of economizer25 to prevent the ow of gases from the latter into hopper 45.

Each of the stoker units 1, 8 and 9 is similar in construction, andisgenerally similar to the stoker shown and described in the lpendingapplication of June E. Beck and AErnst L. Midgette, Serial No. 644,580,led January 31, 1946, now PatentNo. 2,531,719, and to which referencemay be had for a complete disclosure thereof. Inasmuch as the stokerunitsv1, 8 and 9'are similar in construction a description of one willsuffice for all. For convenience, a description will be given of stokerunit 1, and upon reference to Figs. 1 and 2 it will be observed thatsaid stoker unit comprises an endless traveling grate 50, which ismounted upon a lsupporting framework 5|. Traveling grate 50, as shownherein, is comprised of two sections 50a and 50h, disposed in side byside relation, although it is apparent that a greater or lesser numberof such sections may be provided, if so desired, without departing fromthe invention.v Framework 5| comprises a series of I-beams 52 extendinglengthwise of the grate 50 which in turn are mounted upon a series oftransverse I-beams 53. The transverse I-beams 53 for stoker units 1 and9 may be supported at the outer ends thereof on transverse I-beams 53eand 53b mounted adjacent front and rear walls 2 and 3 respectively andat their inner ends on supporting structures indicated generally at 53and 53d. The transverse I-beams 53 for stoker unit 8 are supported atthe opposite ends thereof on supporting structures indicated generallyat 53e and 53f.

Sprocket wheels 54 and 55 are secured to shafts 56 and 51 respectively,which are mounted in any suitable'bearings providednear the outer endsof framework 5|. Chains (not shown). to which the grate bars 58 of grate50 are pivotally attached, are trained over sprgcket wheels 54 and 55.Shaft 51 is actuated by any suitable operating mechanism, such as thatshown in the pending application, Serial No. 644,580, previouslyreferred to herein. v

The right hand end (Figi-2). of stoker unit 1 extends into an enclosure60 mounted exteriorly of side wall 4. Suitable access doors 6| areprovided in enclosure 60 to enable the operator to observe the fire andotherwise tend to the stoker. The lower end 62 of side wall 4 is spacedfrom grate50 to enable movement of the grate and the fuel or ashesthereon past said wall. In

- operation, shaft 51 is so operated as to cause the upper run 63 ofgrate 50 to move from left to right (Fig. 2). The ashes carried by grate50 are dumped over the right hand end thereof (Fig. 2) and gravitate'into an ash pocket 64 provided beneath the enclosure 60.`

In order to prevent separation of the grate bars 58 as they pass oversprocket wheel 55, retaining shoes 65 are provided. As shown in Fig. 2.,each shoe 65` is rpivotally supported as the upper end of an arm 66which in turn is rigidly connected to a rod 61 mounted in brackets 68secured to thel front end 0f a skid ramp 69. The grate bars 58 are alsoheld in Contact with each other as they pass over the inclined surface1|) of skid ramp 69.

Air for combustion purposes is supplied to plenum chamber 39 from ducts35 and 36, as previously described. The air in chamber 39 passesupwardly between the grate bars 58 and into the combustion chamber 6 inthe usual fashion. In order to prevent the escape of air beyond theintermediate extremities of stoker unit 1, suitable sealing means isprovided. As shown in Fig. 2, a vertical sealing plate 12 forms one endwall of chamber 39. Plate 12 is curved at the upper end thereof so as toextend part' around the left handfend of stoker unit 1. inclined plate13 extends between the top of plate 12 and-the inner surface'14 of sidewall 5. A sealing plate 15 interlockingly engages the upper end of plate12 and'rests upon the upper surface of the grate bars 58. A secondsealing plate 16 is provided beneath the grate bars 58 near the righthand end (Fig. 2) of stoker unit 1. A weighted lever 11 engages theunderside of sealing plate 16 and resiliently retains the latter inengagement with the grate bars 58.

A hopper 18 is provided beneath stoker unit 1 for receiving the siftingspassing between the grates 58 thereof. These siftings may be removedfrom time to time through a spout 8U connected to the lower end ofhopper 18.

Fuel 'is .fed to and distributed over grate 56 by rotors 8|, 8|. Rotors8|, 8| are rotatably mounted exteriorly of side wall 4 and propel thefuel through openings 82, 82 provided in said wall. Conveying mechanisms83, 83 convey fuel from hoppers 84, 84 disposed thereabove to the rotors8|, 8|, the said hoppers in turn receiving fuel from an overhead bunker85 through communieating spouts 86, 86. Two fuel feeding anddistributing rotors and associated apparatus are shown for each of thestoker units 1, 8 and 9. It is apparent, however, that a greater orlesser number of such rotors and associated apparatus may be providedfor each stoker, if it is so desired, without departing from theinvention.

The feeding and distributing rotors 8|, 8| may be of any suitable type,such, for example, as that shown and described in the'pendingappliafnemer cationof Ernst L. :Midgette andfRobert'W". Reid, Serial No.599,812, .nledJune 1'6,:19.45,now1?at ent No. 2,511,935. I

l,As shown more p-articularly in.FigS. V1 and 3, a water-cooled screen.90 is provided between Stokerv units 1 and 8. Wa'tere'cooled screen '90.comprises a series of vertically disposed tubes 9| connected to and`extending upwardlyifrom a header 92 supported upon a resilientsupporting member 93 provided between the lower end .of header 92 and atransverse supporting I-beam 94. The lower portions 95 of tubes 9| liein substantially. Vthe same plane and have protective blocks 9B and 91provided respectively atopposite sides thereof. In order to facilitatethepassage of furnace gases between stoker units 'I andx, alternatelydisposed tubesV Bla and '9|1) are bent slightly to the left andright(Fig. 1). respectively, as shown at 98 and 99. Thetubesthencontinueupwardly in substantially parallel relation,.and arethen bent forwardlyand upwardly asshown at|| and |02. The tubes are then bent rearwardlyand upwardlyasshown at |03 and '|04, and the'upper extremities |05thereof then'continue in substantially the same plane and terminate attheir upper ends insteam drum I2.. By providing a resilient support 93for header 92, the water wall is free to expand and contract due to thechanging temperature conditionsin the furnace.

A second water-cooled screen |01 is provided between Stoker units 8 and9. Water-cooled screen |01 is generally similar in construction towater-cooled screen 90 and also comprises v a series of verticallydisposed tubes |08 extending upwardly from a header |09. Header |09 ismounted upon a resilientsupport |10, rextending between the bottomofsaid header and a transverse supporting I-beam `I The opposite sidesof the lower portions l2 of tubes |08 are provided with protectiveblocks. |I|3 and ||4 as Shown in Figs. 1 and 3. The alternately disposedtubes |08a and |081) of water-cooled screen`|01 are 'ben-t tothe leftand to the right as shown .at .I I5 'and IIE, and then extend verticallyin Vsubstantially parallel relation. The alternately vdisposed tubes|08a and |081) are then bent upwardly and for-l wardly as shown at |1and I8, and thenfare bent upwardly so as .to extend in substantially.the same plane as shown at ||9 and |-20,\.and terminate .at their upperends in steam `drum 12. By separating the alternately disposed tubes inthis manner movement ofthe furnace gases between the said tubes isfacilitated.

.A water wall |23 is provided adjacentthe in. terior of front wall .2.Water wall |23 comprises a series of vertically disposed and parallellyarranged tubes v|24, which areconnected at their, lower ends to a header|25. Header .|25 is mounted upon a resilient supportingmember |126lwhich in turn is mounted upon a transverse supporting I-beam |21. Theupper ends of tubes |24 are bent rearwardly as shown at |28, andterminate at their upwardly and rearwardly-disu posed ends in steam druml2.

A water wall |is also provided adjacent rear wall v3. Water wall |30comprises a seriesof verl-Y tically disposed and parallelly arrangedfluid con ducting tubes |3|, which .are connected ,at their lower endsto a header |32. lHeaderY |32 is mounted upon a resilient supportingmember |33 disposed between the lower end -of said .header anda-transVerse supporting I-beam |134. f The upper ends of tubes |3`|are-bent `forwardlyfand slightly upwardly as shown vat |35,at!!'slfthen,ared

bent upwardly and.- rearwardly as shown .at 'l 3E.' and terminate attheir v upper ends in mud drum- |32, frontl and rear'water walls |23 and|30 are also free to expand and contract due yto the changingtemperature conditions in thefurnace. During operation of the furnace,the furnace gases flow in the direction of the arrows-shown in Fig. 1and pass between the'tubes of watercooled screens 9|)l and |01.,andfthence :iiow through the boiler Il around bailles;2|,.2|s, 2|1) and2|, and then enter the lower end of: economizer 25. through economizerA25 andA into duct 26, thence through induction fan 21,*outlet duct 29and4 into stack 28.

lBy arranging water-cooled screensand |01: in the manner shown, aconsiderable quantity of the heat generated in the furnace isabsorbedthereby, since they are disposed in the combustion chamber andlie in the hottest portions of the furnace.

Water walls |23 and V|30 also absorb a'considerable quantity of the heatgenerated and add materially to thesteam generated in the system.V

Thewater-cooled screens 90 and |01 and water walls |23 and |30, togetherwith the banks 'of tubes I6, |1 and I8 ofboiler Il, constitute aneicient steam generating system, which operates atL maximum efficienciesunder all conditions of Operation.

By dividing thesto-ker l0 into units 1), 8 and 9,

l ing from the invention. y

Figs. 5 and 6 disclose an Valternate constructionv wherein ring of theboiler is effected from both of the side walls ofthe furnace. As showntherein numeral |42 designates a furnace comprising front and rear walls|43 and |44 respectively and side walls.|45 and |46. A Stoker |41comprising` units |481), |481), |4911, |491) and |5021, |501) isprovided in the furnace and constitutes `the bottom wall ofthecombustion chamber 15| thereof. The pairs of stoker units |489, |481),|491), '|491' and |502),A |501) are disposed in end to end relation; andall the units are generally similar in construction. The said Stokerunits are also generally. similar in construction to the stokerunitsvfl. 8 and 9 previously described. Accordingly, because of thesimilarity ofthe Stoker units shown in Figs. 5 and 6, a 'description ofone pair of such units will suffice for all, and for convenience a briefdescription will -now be .given of Stoker units' Stoker unit |48acomprises a traveling grate |52, consistingof aseries ofgratebars |53mounted upon a supporting framework |54. Sprocket 7,5 wheels |55-and156,mounted respectively` In View of the resilient supports provided forheaders |25 Vand- The gases then flow upwardly shafts |51 and|58'journalled in bearings providednear the opposite ends of framework|54, have trained thereover vchains (not shown) to which the grate bars|53 are Apivotally attached. The front end of Stoker unit |48aextendsinto an enclosure |60 disposed exteriorly of Side wall |45. Shaft |58 isoperatively connected to any suitable operating mechanism, such, forexample, as that shown and described in the previously referred topending application, Serial No. 599,812, and to which reference may behad for a full disclosure thereof. y

. Upon operation of shaft |58, the upper run |59 of grate |52 is causedto move from left to right (Fig. causing the ashes carried thereby to bedumped over the right hand end of the Stoker. The ashes so dumpedgravitate into an ash pocket |62 disposed beneath enclosure |60, fromwhich they may be removed from time to time by any suitable means.

The Siftings Ipassing between the grate bars |53 of Stoker unit |48agravitate into a hopper |63 disposed beneath said Stoker. A spout |64 isconnected to the lower end of hopper |63, which conducts the siftings toany suitable place of disposal. Air for combustion purposes is suppliedto the Stoker unit |88a by any suitable fan or blower mechanism (notshown), the said air being conducted to a plenum chamber |66, disposedbeneath saidstoker unit by means of a communicating duct |65 and abranch duct |61.

The left hand end (Fig. 5) of the plenum chamber |66 is bounded by anend plate |68, which is curved at the upper end thereof. as shown at|69, so as to extend around a portion of the left hand end of Stokerunit |488.

A sealing plate |12 engages the upper end of end plate |68 and restsupon the grate bars |53 of traveling grate |52. Sealing plate |12extends transversely of the Stoker unit |88a and may be attached to endplate |68 in any suitable manner. A Secondv sealing plate |13 isprovided beneath the grate |52, near the right hand end (Fig. 5) ofStoker unit |483, and a weighted lever |14 retains the plate |13 inengagement with the Said grate.

Fuel is fed and distributed over the grate |52 of the Stoker unit |48ELthrough a pair of openings |15, |15 provided in side wall |45 by feedingrotors |16, |18. Fuel from hoppers |11, |11 is conducted to rotors |16,|16 by any Suitable conveyor mechanisms |18, |18. Hoppers |11, |11 maybe Supplied with fuel from any suitable Yoverhead bunkers (not Shown)through spouts Stoker unit |481El is similar in construction to Stokerunit |488, and also comprises a traveling y grate |82 consisting of aSeries of grate bars |83 mounted upon a supporting framework |84.Sprocket wheels |85 and |86 mounted on shafts |81 and |88, journalled inany Suitable bearings provided respectively near the opposite ends offramework |84, have chains (not shown) trained thereover, to which thegrate bars |83 are pivotal- 1y attached. Shaft |88 is connected to anySuitable operating mechanism (not shown), Such as that disclosed in thepreviously referred to pending application, Serial No. 644,580.

The left hand end (Fig. 5) of Stoker unit |48b extends into an enclosure|89 disposed exteriorly of side wall |46. Shaft |88 is so operated bythe operating mechanism that the upper run |92 of grate |82 is caused tomove from right to left (Fig. 5) of the furnace, causing the ashescarried thereby to be dumped over the left hand end of the Stoker unitand into an ash pocket |93 dis- 8fposed beneath the enclosure |89.Anysiftlngs passing between the grate bars |83 of the grate |82gravitate into a hopper |94 disposed beneath Stoker unit |48b. A spout|95 connected to the lower end of hopper |94 conducts the siftingscollecting in hopper |94 to any suitable place ofv disposal.

Air for combustion is conducted to a plenum chamber |96, disposedbeneath the Stoker unit |48b, by any fan or blower mechanism (notshown). As shown more particularly in Fig. 5, the air from the Said fanor blower is conducted to plenum chamber |96 through a communicatingduct |91 and a branch duct |98. Plenum chamber |96 is closed at one endthereof by an end plate |99, having a curved portion 202 at the upperend thereof, which partly Surrounds the right hand end (Fig. 5) ofStoker unit |481.

A Sealing plate 203, extending transversely of Stoker unit |48b, restsupon the grate bars |83 as they pass around sprocket wheel |85. Sealingplate 203 may be attached to the upper end of plate |99 by any suitablemeans. A second sealing plate 204 is provided beneath the grate bars |83of Stoker unit |48b, near the right hand end thereof, and is held inengagement with the said grate bars by means of a weighted lever 205.

Fuel is fed to and distributed over the grate |82 of Stoker unit |48bthrough openings 206, 206

provided in Side wall |46 by feeding and dis-v tributing rotors 201,201. Fuel from hoppers 208, 208 is conveyed to rotors 201, '201 by meansof any Suitable conveyor mechanisms, Shown generally at 209, 209. Fuelis supplied to the hoppers 208, 208 from overhead bunkers (not shown)through the spouts 2|2, 2|2.

The upper ends of end plates |68 and |99 have extending upwardly andinwardly thereof plates 2|3 and 2|4, which have air openings 2|5 and 2|6provided therein through which secondary air may enter the combustionchamber |5| above Stoker units |48EL and |48b. As shown moreparticularly in Fig. 5, end plates |63 and |99 are spaced apart to forma duct 2|1, which communicates with the communicating duct |91.Accordingly, a portion of the air from communicating duct |91 will flowupwardly into duct 2|1 and then emerge into combustion chamber |5|through openings 215 and 2|6 provided in plates 2|3 and 2|4respectively.

A water-cooled Screen 220 is provided between Stoker units |488, |48band |499', |498. cooled screen 220 comprises two rows of verticallydisposed uid conducting tubes 22| and 222. The lower ends of tubes 22|and 222 are connected to headers (not shown) mounted in any suitablemanner Ibeneath Stoker |41. The lower portions of the opposite sidesrespectively of tubes 22| and 222 are covered by protective blocks 223and 224-, as Shown in Figs. 5 and 6. 'Ihe intermediate portions ofalternately diS- posed tubes 22| and 222 are bent outwardly, as shown inFig. 7, so as to facilitate the passage of furnace gases therebetween.The said tubes 22| and 222 then continue upwardly through combustionchamber |5| similarly to tubes 9| of water-cooled screen 90, previouslydescribed, and terminate at their upper ends in one of the steam drumsof a boiler (not Shown).

A second water-cooled screen 226 is disposed between Stoker units |49,|49 and-|50-, |501. Water-cooled screen 226 is similar in constructionto water-cooled screen 220, and also com- Waterare connected at theirlower ends to headers (not shown) disposed beneath Stoker |41. Theopposite sides of the lower portions of tubes 221 and 228 have providedthereon protective blocks 229 and 232 respectively. The tubes 221 and228 extend upwardly through the combustion chamber similarly to tubes||2 of water wall |93, and the portions disposed above the protectiveblocks 229 and 232 are bent outwardly similarly to the tubes 22| and222, as shown in Fig. '1, so as to facilitate the passage of furnacegases therebetween. The tubes then continue upwardly similarly to thetubes |I2 of water wall H38 and terminate at their upper ends in one ofthe steam drums of the boiler (not shown).

Front wall |43 also has provided interiorly thereof a water wall 233.Water wall '233 comprises a series of vertically disposed, parallellyarranged fluid conducting tubes 234, which are connected at their lowerends to a header (not shownl, disposed beneath the Stoker |41. The tubes234 extend upwardly along wall |43 similarly to the tubes |24 of waterwall |23, and are then bent inwardly, and also terminate in one of thesteam drums of the boiler (not shown).

Rear wall |44 has also mounted interiorly thereof a water wall 236,consisting of a series of vertically disposed and parallelly arrangeduid conducting tubes 231, which are connected at their lower ends to aheader (not shown) disposed beneath stoker |41. Water wall 236 issimilar to the water wall shown in Fig. 1 and the tubes thereof extendupwardly along the rear wall and are then bent forwardly and terminateat their upper ends in the mud drum of the boiler (not shown).

Water-cooled screens 220 and 226, as shown, are comprised of two rows offluid conducting tubes. It is apparent, however, that water-cooledscreens consisting of a greater or lesser number of rows of tubes may beprovided, if it is so desired, without departing from the invention.

From the Vforegoing description it is seen that novel and highlyefficient Stoker furnaces have been provided, which are capable ofoperating at the highest eiciencies under all conditions of operation.The stoker furnaces herein shown and described are particularly adaptedfor use in connection with the larger boiler units; although they may beemployed with equal efi'iciency in smaller units. By arranging the unitsas herein shown and described, the entire grate area of the furnace maybe effectively utilized, and as a result the furnace may be operatedefficiently at the highest capacities. l

It is apparent that the constructions herein shown and described may bemodified to meet the requirements of the different types of furnaces andboiler installations without departing from the invention. Accordingly,while the embodiments of the invention herein shown and described areadmirably adapted to fulfill the objects primarily stated, it is to beunderstood that it is not intended to limit the invention thereto, sinceit may be embodied in other forms,

all coming within the Scope of the claims which follow.

What is claimed is:

1. In a boiler furnace having front and rear end and side walls defininga combustion chamber, boiler drums extending transversely between saidside walls, and boiler tubes in transverse banks connected to said drumsand forming with the latter a boiler assembly above Said chamber.

Stoker means forming the bottom wall of said combustion chamber andcomprising a plurality of individual sections each extending endwise between said Side walls and in side-by-side relation so that the fuel andash move across the furnace, a fluid cooled screen in the form of anupwardly extending transversely disposed bank of fluid conducting tubeslocated between each adjoining pair of said Stoker sections andconnected to said drums, means for feeding fuel to each of said Stokersections through a side wall of the furnace, and means for directing theflow of combustion gases from the said Stoker sections laterally throughSaid screens to and over a common path traversing the drums and tubes ofthe Said boiler.

2. A boiler furnace according to claim 1 wherein the boiler comprisesupper and lower drums, and wherein further the said combustion gasdirecting means includes upper and lower baffles extending respectivelyfrom the front and rear ends of the combustion chamber transversely overthe Stoker sections to the said upper and lower drums and forming ineffect the top wall of said chamber.

3. A boiler furnace according to claim 2 wherein the upper and lowerbaiiies extend over the upper and under the lower drums respectively andin spaced relation to the latter, the said lower baffle comprising aportion inclined downwardly and rearwardly from the boiler andterminating at'the lower end thereof in an ash receiving hopper.

JOSEPH S. BENNETT.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 772,435 Sewell Oct. 18, 19041,106,453 Jacobus Aug. 11, 1914 1,931,948 Armacost Oct. 24, 19331,939,535 Badenhausen Dec. 12, 1933 2,057,622 Webster et al. Oct. 13,1936 2,110,452 Moyer Mar. 8, 1938 2,111,605 Bennett Mar. 22, 19382,139,348 Badenhausen Dec. 6, 1938 2,167,545 Duram rJuly 25, 19392,182,782 Barnes Dec. 12, 1939 2,182,783 Barnes Dec. 12, 1939 2,305,611Frisch Dec. 22, 1942 2,416,053 Grossman Feb. 18, 1947 FOREIGN PATENTSNumber Country Date 538,008 Great Britain July 16, 1941

